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  • 1
    Online Resource
    Online Resource
    A Comparison of Different Methods to Measure Body Temperature During Exercise in the Heat : 821
    Ovid Technologies (Wolters Kluwer Health) ; 2006
    In:  Medicine & Science in Sports & Exercise Vol. 38, No. Supplement ( 2006-05), p. S57-
    Details
    In: Medicine & Science in Sports & Exercise, Ovid Technologies (Wolters Kluwer Health), Vol. 38, No. Supplement ( 2006-05), p. S57-
    Type of Medium: Online Resource
    ISSN: 0195-9131
    URL: Article
    DOI: 10.1249/00005768-200605001-01133
    RVK:
    ZX 1000
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2006
    detail.hit.zdb_id: 2031167-9
    SSG: 31
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  • 2
    Online Resource
    Online Resource
    Simulating nonsorted circle development in arctic tundra ecosystems
    American Geophysical Union (AGU) ; 2008
    In:  Journal of Geophysical Research Vol. 113, No. G3 ( 2008-07-15)
    Details
    In: Journal of Geophysical Research, American Geophysical Union (AGU), Vol. 113, No. G3 ( 2008-07-15)
    Type of Medium: Online Resource
    ISSN: 0148-0227
    URL: Article
    DOI: 10.1029/2008JG000682
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2008
    detail.hit.zdb_id: 2033040-6
    detail.hit.zdb_id: 3094104-0
    detail.hit.zdb_id: 2130824-X
    detail.hit.zdb_id: 2016813-5
    detail.hit.zdb_id: 2016810-X
    detail.hit.zdb_id: 2403298-0
    detail.hit.zdb_id: 2016800-7
    detail.hit.zdb_id: 161666-3
    detail.hit.zdb_id: 161667-5
    detail.hit.zdb_id: 2969341-X
    detail.hit.zdb_id: 161665-1
    detail.hit.zdb_id: 3094268-8
    detail.hit.zdb_id: 710256-2
    detail.hit.zdb_id: 2016804-4
    detail.hit.zdb_id: 3094181-7
    detail.hit.zdb_id: 3094219-6
    detail.hit.zdb_id: 3094167-2
    detail.hit.zdb_id: 2220777-6
    detail.hit.zdb_id: 3094197-0
    SSG: 16,13
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  • 3
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    Landslide Mapping Using Multiscale LiDAR Digital Elevation Models
    Association of Environmental and Engineering Geologists ; 2020
    In:  Environmental and Engineering Geoscience Vol. 26, No. 4 ( 2020-11-01), p. 405-425
    Details
    In: Environmental and Engineering Geoscience, Association of Environmental and Engineering Geologists, Vol. 26, No. 4 ( 2020-11-01), p. 405-425
    Abstract: This study presents a new methodology to identify landslide and landslide-susceptible locations in Interior Alaska using only geomorphic properties from light detection and ranging (LiDAR) derivatives (i.e., slope, profile curvature, and roughness) and the normalized difference vegetation index (NDVI), focusing on the effect of different resolutions of LiDAR images. We developed a semi-automated object-oriented image classification approach in ArcGIS 10.5 and prepared a landslide inventory from visual observation of hillshade images. The multistage work flow included combining derivatives from 1-, 2.5-, and 5-m-resolution LiDAR, image segmentation, image classification using a support vector machine classifier, and image generalization to clean false positives. We assessed classification accuracy by generating confusion matrix tables. Analysis of the results indicated that LiDAR image scale played an important role in the classification, and the use of NDVI generated better results. Overall, the LiDAR 5-m-resolution image with NDVI generated the best results with a kappa value of 0.55 and an overall accuracy of 83 percent. The LiDAR 1-m-resolution image with NDVI generated the highest producer accuracy of 73 percent in identifying landslide locations. We produced a combined overlay map by summing the individual classified maps that was able to delineate landslide objects better than the individual maps. The combined classified map from 1-, 2.5-, and 5-m-resolution LiDAR with NDVI generated producer accuracies of 60, 80, and 86 percent and user accuracies of 39, 51, and 98 percent for landslide, landslide-susceptible, and stable locations, respectively, with an overall accuracy of 84 percent and a kappa value of 0.58. This semi-automated object-oriented image classification approach demonstrated potential as a viable tool with further refinement and/or in combination with additional data sources.
    Type of Medium: Online Resource
    ISSN: 1078-7275
    URL: Article
    DOI: 10.2113/EEG-2268
    Language: English
    Publisher: Association of Environmental and Engineering Geologists
    Publication Date: 2020
    detail.hit.zdb_id: 2179189-2
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  • 4
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    Online Resource
    Investigating Movement and Characteristics of a Frozen Debris Lobe, South-Central Brooks Range, Alaska
    Association of Environmental and Engineering Geologists ; 2016
    In:  Environmental & Engineering Geoscience Vol. 22, No. 3 ( 2016-08), p. 259-277
    Details
    In: Environmental & Engineering Geoscience, Association of Environmental and Engineering Geologists, Vol. 22, No. 3 ( 2016-08), p. 259-277
    Type of Medium: Online Resource
    ISSN: 1078-7275
    URL: Article
    DOI: 10.2113/gseegeosci.22.3.259
    Language: English
    Publisher: Association of Environmental and Engineering Geologists
    Publication Date: 2016
    detail.hit.zdb_id: 2179189-2
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  • 5
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    Online Resource
    Arctic riparian shrub expansion indicates a shift from streams gaining water to those that lose flow
    Springer Science and Business Media LLC ; 2020
    In:  Communications Earth & Environment Vol. 1, No. 1 ( 2020-11-18)
    Details
    In: Communications Earth & Environment, Springer Science and Business Media LLC, Vol. 1, No. 1 ( 2020-11-18)
    Abstract: Shrub expansion has been observed across the Arctic in recent decades along with warming air temperatures, but tundra shrub expansion has been most pronounced in protected landscape positions such as floodplains, streambanks, water tracks, and gullies. Here we show through field measurements and laboratory analyses how stream hydrology, permafrost, and soil microbial communities differed between streams in late summer with and without tall shrubs. Our goal was to assess the causes and consequences of tall shrub expansion in Arctic riparian ecosystems. Our results from Toolik Alaska, show greater canopy height and density, and distinctive plant and soil microbial communities along stream sections that lose water into unfrozen ground (talik) compared to gaining sections underlain by shallow permafrost. Leaf Area Index is linearly related to the change in streamflow per unit stream length, with the densest canopies coinciding with increasingly losing stream sections. Considering climate change and the circumpolar scale of riparian shrub expansion, we suggest that permafrost thaw and the resulting talik formation and shift in streamflow regime are occurring across the Low Arctic.
    Type of Medium: Online Resource
    ISSN: 2662-4435
    URL: Article
    DOI: 10.1038/s43247-020-00050-1
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2020
    detail.hit.zdb_id: 3037243-4
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  • 6
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    Spatial patterns of arctic tundra vegetation properties on different soils along the Eurasia Arctic Transect, and insights for a changing Arctic
    IOP Publishing ; 2021
    In:  Environmental Research Letters Vol. 16, No. 1 ( 2021-01-01), p. 014008-
    Details
    In: Environmental Research Letters, IOP Publishing, Vol. 16, No. 1 ( 2021-01-01), p. 014008-
    Abstract: Vegetation properties of arctic tundra vary dramatically across its full latitudinal extent, yet few studies have quantified tundra ecosystem properties across latitudinal gradients with field-based observations that can be related to remotely sensed proxies. Here we present data from field sampling of six locations along the Eurasia Arctic Transect in northwestern Siberia. We collected data on the aboveground vegetation biomass, the normalized difference vegetation index (NDVI), and the leaf area index (LAI) for both sandy and loamy soil types, and analyzed their spatial patterns. Aboveground biomass, NDVI, and LAI all increased with increasing summer warmth index (SWI—sum of monthly mean temperatures 〉 0 °C), although functions differed, as did sandy vs. loamy sites. Shrub biomass increased non-linearly with SWI, although shrub type biomass diverged with soil texture in the southernmost locations, with greater evergreen shrub biomass on sandy sites, and greater deciduous shrub biomass on loamy sites. Moss biomass peaked in the center of the gradient, whereas lichen biomass generally increased with SWI. Total aboveground biomass varied by two orders of magnitude, and shrubs increased from 0 g m −2 at the northernmost sites to 〉 500 g m −2 at the forest-tundra ecotone. Current observations and estimates of increases in total aboveground and shrub biomass with climate warming in the Arctic fall short of what would represent a ‘subzonal shift’ based on our spatial data. Non-vascular (moss and lichen) biomass is a dominant component ( 〉 90% of the photosynthetic biomass) of the vegetation across the full extent of arctic tundra, and should continue to be recognized as crucial for Earth system modeling. This study is one of only a few that present data on tundra vegetation across the temperature extent of the biome, providing (a) key links to satellite-based vegetation indices, (b) baseline field-data for ecosystem change studies, and (c) context for the ongoing changes in arctic tundra vegetation.
    Type of Medium: Online Resource
    ISSN: 1748-9326
    URL: Article
    DOI: 10.1088/1748-9326/abc9e3
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2021
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  • 7
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    Online Resource
    Hillslope erosional features and permafrost dynamics along infrastructure in the Arctic Foothills, Alaska
    Wiley ; 2023
    In:  Permafrost and Periglacial Processes Vol. 34, No. 2 ( 2023-04), p. 208-228
    Details
    In: Permafrost and Periglacial Processes, Wiley, Vol. 34, No. 2 ( 2023-04), p. 208-228
    Abstract: Abrupt thaw of ice‐rich permafrost in the Arctic Foothills yielded to the formation of hillslope erosional features. In the infrastructure corridor, we observed thermal erosion and thaw slumping that self‐healed near an embankment. To advance our understanding of processes between infrastructure and hillslope erosional features (INF‐HEF), we combined climate and remote sensing analyses to field investigations to assess an INF‐HEF system and validate our findings in a broader area along the infrastructure corridor. We identified that thaw consolidation along an embankment formed a thermokarst ditch that was ubiquitous in the broader study area, and which was extensively affected by shrubification and supported other positive feedback (e.g., snow accumulation, water impoundment, and weakened vegetation mat). The thermokarst ditch facilitated channelization of cross‐drainage water, thus increasing the terrain vulnerability to thermal erosion that evolved into thaw slumping after heavy rainfalls. The terrain resilience to thaw slumping benefited from the type of ground ice and topography prevailing at our site. The lateral discontinuity of massive ice in an ice‐wedge polygonal system (i.e., interchange soil and massive ice) compounded to a low‐slope gradient with topographic obstacles (e.g., baydzherakhs) decreased slumping activity and supported self‐stabilization.
    Type of Medium: Online Resource
    ISSN: 1045-6740 , 1099-1530
    URL: Issue
    URL: Article
    DOI: 10.1002/ppp.v34.2
    DOI: 10.1002/ppp.2188
    RVK:
    RA 1000
    Language: English
    Publisher: Wiley
    Publication Date: 2023
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    SSG: 14
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  • 8
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    Online Resource
    Pan-Arctic ice-wedge degradation in warming permafrost and its influence on tundra hydrology
    Springer Science and Business Media LLC ; 2016
    In:  Nature Geoscience Vol. 9, No. 4 ( 2016-4), p. 312-318
    Details
    In: Nature Geoscience, Springer Science and Business Media LLC, Vol. 9, No. 4 ( 2016-4), p. 312-318
    Type of Medium: Online Resource
    ISSN: 1752-0894 , 1752-0908
    URL: Article
    DOI: 10.1038/ngeo2674
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2016
    detail.hit.zdb_id: 2396648-8
    detail.hit.zdb_id: 2405323-5
    SSG: 16,13
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  • 9
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    Online Resource
    An Object-Based Approach for Mapping Tundra Ice-Wedge Polygon Troughs from Very High Spatial Resolution Optical Satellite Imagery
    MDPI AG ; 2021
    In:  Remote Sensing Vol. 13, No. 4 ( 2021-02-04), p. 558-
    Details
    In: Remote Sensing, MDPI AG, Vol. 13, No. 4 ( 2021-02-04), p. 558-
    Abstract: Very high spatial resolution commercial satellite imagery can inform observation, mapping, and documentation of micro-topographic transitions across large tundra regions. The bridging of fine-scale field studies with pan-Arctic system assessments has until now been constrained by a lack of overlap in spatial resolution and geographical coverage. This likely introduced biases in climate impacts on, and feedback from the Arctic region to the global climate system. The central objective of this exploratory study is to develop an object-based image analysis workflow to automatically extract ice-wedge polygon troughs from very high spatial resolution commercial satellite imagery. We employed a systematic experiment to understand the degree of interoperability of knowledge-based workflows across distinct tundra vegetation units—sedge tundra and tussock tundra—focusing on the same semantic class. In our multi-scale trough modelling workflow, we coupled mathematical morphological filtering with a segmentation process to enhance the quality of image object candidates and classification accuracies. Employment of the master ruleset on sedge tundra reported classification accuracies of correctness of 0.99, completeness of 0.87, and F1 score of 0.92. When the master ruleset was applied to tussock tundra without any adaptations, classification accuracies remained promising while reporting correctness of 0.87, completeness of 0.77, and an F1 score of 0.81. Overall, results suggest that the object-based image analysis-based trough modelling workflow exhibits substantial interoperability across the terrain while producing promising classification accuracies. From an Arctic earth science perspective, the mapped troughs combined with the ArcticDEM can allow hydrological assessments of lateral connectivity of the rapidly changing Arctic tundra landscape, and repeated mapping can allow us to track fine-scale changes across large regions and that has potentially major implications on larger riverine systems.
    Type of Medium: Online Resource
    ISSN: 2072-4292
    URL: Article
    DOI: 10.3390/rs13040558
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2513863-7
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  • 10
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    Online Resource
    21st-century modeled permafrost carbon emissions accelerated by abrupt thaw beneath lakes
    Springer Science and Business Media LLC ; 2018
    In:  Nature Communications Vol. 9, No. 1 ( 2018-08-15)
    Details
    In: Nature Communications, Springer Science and Business Media LLC, Vol. 9, No. 1 ( 2018-08-15)
    Abstract: Permafrost carbon feedback (PCF) modeling has focused on gradual thaw of near-surface permafrost leading to enhanced carbon dioxide and methane emissions that accelerate global climate warming. These state-of-the-art land models have yet to incorporate deeper, abrupt thaw in the PCF. Here we use model data, supported by field observations, radiocarbon dating, and remote sensing, to show that methane and carbon dioxide emissions from abrupt thaw beneath thermokarst lakes will more than double radiative forcing from circumpolar permafrost-soil carbon fluxes this century. Abrupt thaw lake emissions are similar under moderate and high representative concentration pathways (RCP4.5 and RCP8.5), but their relative contribution to the PCF is much larger under the moderate warming scenario. Abrupt thaw accelerates mobilization of deeply frozen, ancient carbon, increasing 14 C-depleted permafrost soil carbon emissions by ~125–190% compared to gradual thaw alone. These findings demonstrate the need to incorporate abrupt thaw processes in earth system models for more comprehensive projection of the PCF this century.
    Type of Medium: Online Resource
    ISSN: 2041-1723
    URL: Article
    DOI: 10.1038/s41467-018-05738-9
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2018
    detail.hit.zdb_id: 2553671-0
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